Advances in the field of computer graphics have revolutionized the digital space and have added convenience and finesse to the modern print technologies. Elements in the digital space are produced either as image-based graphics or object-based graphics for printing. The image-based (or raster) graphics use raster objects that measure various aspects, for example, hue, saturation, and intensity that describe color at predetermined set of locations, i.e., a grid of pixels, to represent an image. In contrast, the object-based graphics represent an image using graphics objects made up of primitive or geometric entities such as lines, polygons, circles, Bezier curves, and so on. Each graphics object is based on vectors that extend through control points or nodes, which have a definite location on a two-dimensional plane and determine the direction of a path followed by the graphics object. The path, and so the corresponding graphics object, has various attributes such as stroke, outline (or border), color, shape, curve, thickness, and fill.
Each graphics object is made up of one or more strokes that define a curve representing the shape of the graphics object. Such curve may form an outline, or a part thereof, that interfaces between the graphics object and the background. The outline can define one or more enclosed regions called as fill regions to create a fill graphics object (or just, fill object), where the outline may have a color different from fill colors of one or more enclosed regions.
Unlike the raster objects, the graphics objects can be layered, dynamically sized with changing device resolutions, and occupy relatively less memory. As a result, the graphics objects are a preferred choice to represent logos, fonts, illustrations, etc., in a high production imaging environment such as a heterogeneous printer workflow environment (e.g., FreeFlow® Print Server), where the image quality holds supreme importance. However, conventional approaches may fail to improve the image quality of graphics objects, especially the fill objects.
State-of-the-art approaches such as region growing algorithms, which are based on stroke thickening, may cause fill objects having light strokes such as thin curves to fade out or disappear. For example, when a fill object has a color (e.g., white) of the outline different than a fill color (e.g., black), but same as the background color (i.e., white), the existing approaches may cause the fill object to fade out while growing or thickening the outline. Moreover such stroke thickening techniques often grow or thicken the outline to overlap a fill region, or a part thereof, of the fill object and can cause the fill color to get replaced by the color of the outline. As a result, an original appearance of the fill object may change, especially when the fill object has a thin fill region. Such content loss and appearance variation (or content distortion) in the fill objects results in a degraded image quality output and hampers production performance.
Therefore, there exists a need for a robust technique that improves the quality of graphics objects, particularly fill objects, without any loss of data or content.